I LP and HP all over the place, sometimes subtle, sometimes not. Really just depends on what I'm working with and how the mix is sounding as a whole.
I'll HP stuff that won't benefit from those lows and only muddy up the mix IMO. Different elements may benefit from more or less or even none. Vocals, Guitars, Snares, sometimes Bass, etc. will usually get a HP in varying degrees.
I'm also an obsessive A/B'er and compare everything a million times over just to see what exactly it's doing and if it's needed..
As for LPF, the usual suspects. Guitar, OH's slightly, vocals occasionally.
Basically, just experiment and do what sounds good!
Hope I was some help,
Charlie